36 



MASS. EXPERIMENT STATION BULLETIN 249 



largest collections ranging from June 10 in 1927 to June 22 in 1926. Stragglers 

 continued in the trees until the last week in July each year, although it is 

 probable that some of the later collections included insects which migrated 

 from un jarred trees. 



PigTire 4. Time of Appearance of the Plnm Curculio in Apple Trees in the 

 Spring-, as Obtained from Jarring- Records. 



Period of Oviposition 



During the three years of study, oviposition has begun about June 1. By 

 June 15 this activity has increased to normal proportions and the number 

 of eggs deposited continued to be large until July 15. As shown in Figure 

 5, the greatest number of eggs was laid between June 21 and June 30 each 

 year, usually following closely the appearance of the greatest number of 

 beetles in the trees. Only in 1928 were eggs found after August 1 and 

 many of those laid during the last week of this period failed to develop. The 

 beetles are quite resistant to climatic changes and the number of eggs laid 

 daily does not vary greatly with the fluctuations in temperature. Normal 

 weather conditions are the most favorable for curculio activity. 



